Currently, navigation devices of moving bodies such as vehicles are known. This navigation device displays a vehicle position on a map displayed on a display device, and gives a guidance to a destination. When a vehicle position is displayed on a road on a map, a GPS positioning device which obtains GPS satellite positioning results and various sensors such as a velocity sensor, an angular velocity sensor and an acceleration sensor are used to observe and measure a vehicle motion and then processing called map matching is performed to identify the vehicle position on a road link of map data.
However, a scale factor for calculating a moving distance and a velocity based on output pulses of a velocity sensor differs per vehicle. Further, zero voltages of an angular velocity sensor and an acceleration sensor fluctuate (drift), and therefore various sensors need to be optionally corrected. To correct various sensors, positioning results transmitted from GPS satellites are generally used for a correction reference value or for correction conditions.
For example, Patent Document 1 discloses a technique of calculating a vehicle velocity in a horizontal direction (a direction on a horizontal plane perpendicular to a vertical direction) based on signals (positioning results) from GPS satellites, and correcting a scale factor based on the calculated vehicle velocity. Further, Patent Document 2 and Patent Document 3 disclose techniques of calculating a pitch angle (an angle formed between a traveling direction of a vehicle and the horizontal plane) based on signals from GPS satellites, and calculating an acceleration of the vehicle in a traveling direction, a gravitational acceleration and a fluctuation of a zero voltage of the acceleration sensor based on the calculated pitch angle.